Integrated socket for microprocessor package and cache memory

ABSTRACT

A socket comprises a socket body having a bottom surface at which the socket can be mounted to a motherboard, a top surface, and several side surfaces. The top surface has an array of electrical contacts at which a package containing a microprocessor can be coupled to the socket. One or more of the side surfaces have a slot, which includes an electrical interface at which a circuit card containing cache memory for use by the microprocessor can be removably inserted into the socket body parallel to the motherboard.

FIELD OF THE INVENTION

[0001] The present invention pertains to sockets used to connectmicroelectronic device packages to circuit boards. More particularly,the present invention relates to a socket which accommodates both amicroprocessor package and cache memory.

BACKGROUND OF THE INVENTION

[0002] Modern computer systems include at least one microprocessor orother similar controlling device, and memory, commonly including severallevels of cache memory. One type of cache memory is located on the samedie as the microprocessor and is referred to as Level 1 or “L1” cache.Typically, the L1 cache includes a very small amount of memory but canbe accessed very quickly by the microprocessor due to its proximity tothe microprocessor. Another type of cache, known as Level 2 or “L2”cache, is normally mounted in the same package as the microprocessor buton a different die. L2 cache typically includes more memory than the L1cache but cannot be accessed as quickly. A third level of cache, knownas Level 3 or “L3” cache, is normally mounted on a separate circuitboard or circuit card from the microprocessor package and typicallyincludes more memory than the L1 and L2 caches. However, the L3 cachecannot be accessed as quickly as the L1 and L2 caches, due to itsgreater distance from the microprocessor.

[0003]FIG. 1 shows an example of an L3 cache card design. An L3 cachedie can be assembled in a wire-bond or flip-chip type of package, andthe package can be surface-mounted on a printed circuit board (PCB)card. Alternatively, the L3-cache die can be directly mounted on a PCBcard with or without encapsulate. Hence, the illustrated design includesa PCB card 1, on which one or more cache memory dies (or packagescontaining such dies) 2 are mounted, and edge fingers 3 to allow the PCBcard to be inserted into an edge connector on a motherboard.

[0004]FIG. 2 shows how the L3 cache card of FIG. 1 can be installed in acomputer system. The L3 cache card 1 can be inserted into an edgeconnector 21 that is mounted on the motherboard 22, a shown. Alsomounted on the motherboard 22 is a socket 23, which allows themicroprocessor package 24 to be coupled to the motherboard 22. A heatsink 25 is thermally coupled to the microprocessor package through apackage heat spreader 26.

[0005] The design of FIGS. 1 and 2 has several disadvantages. First, thedistance between the microprocessor package and the L3 cache isundesirably large, which increases the L3 cache access time. The L3cache card also consumes additional space and requires edge connectorson the motherboard. Further, the L3 cache card tends to block some ofthe airflow through the heat sink, hindering the cooling of othercomponents, such as microprocessor, chipset, and voltage regulators.

[0006] An alternative approach is to mount the L3 cache on the samemicroprocessor package, like a multi-chip module (MCM). However, thecost of such an approach is very high and manufacturing is difficult.

DESCRIPTION OF THE DRAWINGS

[0007] The present invention is illustrated by way of example and notlimitation in the figures of the accompanying drawings, in which likereferences indicate similar elements and in which:

[0008]FIG. 1 shows an L3 cache card;

[0009]FIG. 2 shows the installation of an L3 cache card and amicroprocessor on a motherboard;

[0010]FIG. 3 shows three orthogonal view of a socket according to oneembodiment of the invention;

[0011]FIG. 4 schematically shows the electrical connections within thesocket of FIG. 3; and

[0012]FIG. 5 shows the installation of L3 cache cards and amicroprocessor on a motherboard using a socket in accordance with theinvention.

DETAILED DESCRIPTION

[0013] A socket which accommodates both a microprocessor package andcache memory is described. Note that in this description, references to“one embodiment” or “an embodiment” mean that the feature being referredto is included in at least one embodiment of the present invention.Further, separate references to “one embodiment” in this description donot necessarily refer to the same embodiment; however, neither are suchembodiments mutually exclusive, unless so stated and except as will bereadily apparent to those skilled in the art. For example, a feature,structure, act, etc. described in one embodiment may also be included inother embodiments. Thus, the present invention can include a variety ofcombinations and/or integrations of the embodiments described herein.

[0014] As described in greater detail below, in one embodiment of theinvention, the socket comprises a socket body having a bottom surface atwhich the socket can be mounted to a motherboard, a top surface toaccommodate a microprocessor package, and several side surfaces. One ormore of the side surfaces have a slot that includes an electricalinterface at which a circuit card containing cache memory for use by themicroprocessor can be removably inserted into the socket body parallelto the motherboard.

[0015] As will be apparent from this description, this socket designprovides a significant reduction in the distance between amicroprocessor package and L3 cache (or other device), thereby allowingfaster access by the microprocessor to the L3 cache. This design alsoimproves air flow through the microprocessor's heat sink, allowing formore efficient cooling of the microprocessor and related components.Further, eliminating the traditional L3 cache edge connectors allows themotherboard size to be reduced, which is advantageous forsmall-footprint (e.g., mobile) applications. This design also allows L3cache cards to be upgraded easily. Moreover, with this design the L3cache card can share the same thermal solutions (heat sink, etc.) as themicroprocessor package, if desired. There is also no need to modify thecurrent microprocessor package design.

[0016]FIG. 3 shows three orthogonal views (top, front and side) of asocket according to one embodiment of the invention. A microprocessorpackage can be mounted to the socket of the present invention in thesame way as with the traditional microprocessor socket 23 (FIG. 2). Thatis, a pin grid array (PGA) or ball grid array (BGA) of the package canbe mounted to a corresponding array 31 of electrical contacts on the topsurface of the socket body (hereinafter “socket”) 30. In addition, withthis design, L3 cache cards can be plugged into slots 32 in two sides ofthe socket 30. It will be recognized that the size of the L3 cache cardneeds to be made to match the slots 32 in the socket 30. A socket handle33 facilitates physical handling of the socket 30.

[0017] Note that while the socket 30 is shown to have two slots 32, inother embodiments the socket 30 may have only one slot 32 or more thantwo slots 32. Furthermore, a socket embodying the present invention mayalternatively have a different shape than that illustrated in FIG. 3.

[0018]FIG. 4 schematically shows the electrical connections within thesocket 30. The socket 30 includes electrical connections 41 between thearray 31 on the top surface and the electrical connection to themotherboard at the bottom surface of the socket. The socket 30 alsoprovides electrical connections 42 between the array 31 and anelectrical interface 43 in each of the slots 32, to allow communicationbetween the microprocessor and the L3 cache.

[0019]FIG. 5 shows an example of the installation of L3 cache cards anda microprocessor on a motherboard using a socket in accordance with thepresent invention. When inserted into the socket 30, each L3 cache card51 occupies space below the microprocessor heat sink 25 and is suspendedparallel to the motherboard 22 just above the motherboard 22. Anelastomer or other suitable member 52 can be inserted between the L3cache card 51 and the motherboard 22 as shown, for mechanical support,heat conduction, and electrical insulation. In addition, an elastomer orother suitable member 53 can also be inserted between the L3 cache card51 and the microprocessor heat sink 25, so that the L3 cache can sharethe same thermal solution as the microprocessor. In such an embodiment,the elastomer should have high thermal conductivity and good electricalinsulation.

[0020] Note that while the invention has been described in terms of asocket that accommodates L3 cache and a microprocessor package, thesocket design of the present invention may alternatively be used toaccommodate types of electronic devices other than L3 cache ormicroprocessors, if desired.

[0021] Thus, a socket which accommodates multiple microelectronicdevices has been described. Although the present invention has beendescribed with reference to specific exemplary embodiments, it will beevident that various modifications and changes may be made to theseembodiments without departing from the broader spirit and scope of theinvention as set forth in the claims. Accordingly, the specification anddrawings are to be regarded in an illustrative sense rather than arestrictive sense.

What is claimed is:
 1. A socket comprising: a socket body having a firstsurface and a second surface; a first electrical interface on the firstsurface, to electrically couple a microelectronic device to the socket;and a slot in the second surface, into which a circuit card can beinserted, the slot containing a second electrical interface toelectrically couple the circuit card to the socket.
 2. A socket asrecited in claim 1, further comprising an electrical connection betweenthe first electrical interface and the second electrical interface.
 3. Asocket as recited in claim 2, the socket body further having a thirdsurface, the third surface having a third electrical interface at whichthe socket can be mounted to a circuit board.
 4. A socket comprising: asocket body; a first interface on the socket body, through which aprocessor can be coupled to the socket; and a second interface throughwhich a cache memory, for use by the processor, can be coupled to thesocket.
 5. A socket as recited in claim 4, wherein the second interfaceis to accommodate a circuit card having the cache memory thereon.
 6. Asocket as recited in claim 5, wherein the second interface comprises aslot in the socket body.
 7. A socket as recited in claim 4, wherein thesecond interface allows the cache memory to be non-destructivelydecoupled from the socket.
 8. A socket comprising: a socket body; afirst electrical interface on the socket body, at which a package havinga processor can be coupled to the socket; and a second electricalinterface at which a first circuit card having cache memory, for use bythe processor, can be removably coupled to the socket.
 9. A socket asrecited in claim 8, wherein the second interface comprises a slot in thesocket body.
 10. A socket as recited in claim 8, further comprising athird electrical interface at which a second circuit card having cachememory, for use by the processor, can be removably coupled to thesocket.
 11. A socket comprising: a socket body; first interface meansfor coupling a processor to the socket body; and second interface meansfor removably coupling a cache memory, for use by the processor, to thesocket.
 12. A socket as recited in claim 11, wherein the secondinterface means comprises means for receiving a circuit card having thecache memory thereon.
 13. A socket as recited in claim 11, wherein thesecond interface means comprises means for allowing the cache memory tobe non-destructively decoupled from the socket.
 14. A socket comprising:a socket body having a first surface at which the socket can be mountedto a circuit board; a second surface parallel to the first surface; anda third surface perpendicular to the first surface and the secondsurface; an electrical interface o n the second surface, at which apackage containing a microprocessor can be coupled to the socket; and aslot in the third surface, the slot including an electrical interface atwhich a first circuit card having cache memory for use by themicroprocessor can be removably inserted edgewise into the socket body,to electrically couple the cache memory to the microprocessor.
 15. Asocket as recited in claim 14, wherein the first circuit card isdisposed parallel to the first circuit board when the first circuit cardis inserted into the first slot.
 16. A socket as recited in claim 14,wherein the socket body further has a fourth surface parallel to thethird surface, the socket further comprising a slot in the fourthsurface, the slot in the fourth surface including an electricalinterface at which a second circuit card having cache memory for use bythe microprocessor can be removably inserted edgewise into the socketbody, and disposed parallel to the first circuit board, to electricallycouple the cache memory to the microprocessor.
 17. A socket comprising:a socket body having a first surface at which the socket can be mountedto a first circuit board; a second surface parallel to the firstsurface; and, a third surface and a fourth surface, each perpendicularto the first surface and the second surface; a first electricalinterface on the second surface, at which a package containing amicroprocessor can be coupled to the socket; a slot in the thirdsurface, including an electrical interface at which a first circuit cardcan be removably inserted into the socket body and disposed parallel tothe first circuit board, the first circuit card having cache memory foruse by the microprocessor; and a slot in the fourth surface, includingan electrical interface at which a second circuit card can be removablyinserted into the socket body and disposed parallel to the first circuitboard, the second circuit card having cache memory for use by themicroprocessor.
 18. A socket as recited in claim 17, further comprisinga first member coupled between the first circuit card and the circuitboard.
 19. A socket as recited in claim 18, wherein the first membercomprises a thermal interface to conduct heat away from the firstcircuit card.
 20. A socket as recited in claim 18, further comprising: aheat sink coupled to the package; and a second member coupled betweenthe first circuit card and the heat sink.
 21. An apparatus comprising: apackage including a microprocessor; a circuit board; and a socketcoupled to the package and to the circuit board, the socket including asocket body having a first surface coupled to the circuit board, asecond surface parallel to the first surface and coupled to the package,and a third surface not parallel to the first surface, and a slot in thethird surface, including an electrical interface at which a firstcircuit card can be removably inserted into the socket body and disposedparallel to the circuit board.
 22. An apparatus as recited in claim 21,wherein the first circuit card has disposed thereon cache memory for useby the microprocessor.
 23. An apparatus as recited in claim 21, whereinthe socket body further has a fourth surface, the socket furthercomprising a slot in the fourth surface, including an electricalinterface at which a second circuit card can be removably inserted intothe socket body and disposed parallel to the circuit board.
 24. Anapparatus as recited in claim 23, wherein the second circuit card hasdisposed thereon cache memory for use by the microprocessor.
 25. Anapparatus as recited in claim 21, further comprising a first membercoupled between the first circuit card and the circuit board.
 26. Anapparatus as recited in claim 25, wherein the first member comprises athermal interface to conduct heat away from the first circuit card. 27.An apparatus as recited in claim 25, further comprising: a heat sinkcoupled to the package; and a second member coupled between the firstcircuit card and the heat sink.
 28. An apparatus as recited in claim 21,further comprising a heat sink coupled to the package, wherein the firstcircuit card has cache memory for use by the microprocessor, and whereinthe first circuit card is disposed between the circuit board and theheat sink.